Can You Jump Start a Lawn Mower? (With a Car Battery)

After long winter storage, it is quite common for a lawn mower battery to become flat. This should not be a great deal if you can access a car battery. You can safely jumpstart a riding lawn mower battery with your car battery. Let’s look at how it’s done the right way.

Before you jumpstart your lawn mower battery, you’ll want to be sure that a flat battery is the main reason your riding lawn mower won’t start. Begin by checking the oil and gas levels before you troubleshoot.

Most likely, a battery is a problem if you can hear a clicking sound when trying to start the engine.

Next is to make sure that you have a 12-Volt battery. A sticker or stamp on the battery’s casing will indicate the voltage. You can locate your lawn mower battery under-seat, under-drink the holder, or behind the wheel.

How to Jump Start a Lawn Mower Battery with a Car Battery

To successfully jump-start a lawn mower, you must ensure that both batteries’ terminals and poles are clean, secure, and not damaged. In most cases, long storage can lead to corrosion on the terminals.

A white crusty build-up on the terminals and battery posts can prevent current flow as you jumpstart or charge it.

If that is the case, sprinkle some baking soda on the terminals and add a small amount of water. This will neutralize the acid and make it easy to remove the corrosion.

Next, use a wire brush to clean the terminals and poles. Wipe the surface dry and apply a coat of petroleum jelly to help protect against corrosion.

Before you start, you’ll also need a quality set of jumping cables. Damaged, worn or dirty cables will also fail the boosting process.

Damaged cables may have broken wires within, which cause excessive resistance when power flows. Often, you may notice such cables getting too hot while trying to jump-start your lawn mower.

Caution: Observe safety; you need to have protective eyewear and leather gloves to protect against shock. Work away from children and in a safe place without flammables nearby.

Steps for jumpstarting a battery

  1. Move your vehicle close to the mower or vice versa, turn off the engine, and pop the hood to access the battery. You’ll likely need to remove a plastic cover from the car battery terminals.
  2. Look out for positive and negative markings on the battery casing. Battery poles are commonly colored red for positive (+) and black for negative (-)
  3. Start by connecting the positive red (+) of the mower battery to the red (+) of the car battery.
  4. Now connect the negative black (-) on the car battery to a ground source on the mower. (Any bare metal on the lawn mower)
  5. Start the lawn mower engine and let it run for about 5 minutes before you remove the jumper cables.
  6. Remove the jumpers in a reverse order starting from the black on the ground source, then from the negative (black) of the car battery, followed by the positive (red) of the car battery, and finally from the positive (red) of the lawn mower battery.

When jump starting, you have to make sure that you are starting your riding lawn mower the right way. Otherwise, an open safety sensor may prevent the engine from starting.

If your lawn mower engine does not start, your lawn mower battery is likely dead completely, and you have to replace it with a new one.

Can you charge a lawn mower battery with a car battery?

Charging a lawn mower battery with another battery will not be effective. Typically, it is impossible to charge a 12V battery with another 12V battery directly. The charging process will stop once the two batteries attain the same average charge level.

However, you can jump-start a lawn mower with another fully charged 12-volt battery. You may even use the car battery without having to bring the car around.

When to Charge a Lawn Mower Battery

Riding lawn mower engines rely on battery power to start. The battery must be fully charged for this to work. However, you don’t need to charge your mower’s battery routinely, but probably when your battery is unresponsive, or you are planning storage or startup.

The idea of jumpstarting a lawnmower battery applies only if you don’t have a working charger. But it is always a good idea to have a recommended modern charger for your lawn mower battery.

Most lawn tractors come with a 12-volt battery which also needs a charger of that particular rating. If you have a 6-volt battery, you should not use a 12-volt charger unless it has a setting you can toggle to match the battery voltage.

Fortunately, modern battery chargers have multiple mode settings, including slow, fast, and jumpstart. An integrated charging timer feature also ensures you are not overcharging your lawn mower battery.

Final Thought

You risk a dead battery by storing it for longer without charging. Extremely cold temperatures are known to drain batteries. If you do not plan to recharge your battery, you can jumpstart it using a car battery and get right back on track with your mowing schedules.

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